Question

What will be the electronic configuration of d^5 in terms of t2g and eg in an octahedral field when Δo<P, where P is the energy required for pairing of electrons in a single orbital?

(a) t2g^5 eg^0

(b) t2g^2 eg^3

(c) t2g^3 eg^2

(d) t2g^0 eg^5

The question was asked during an interview.

This is a very interesting question from Bonding in Coordination Compounds topic in division Coordination Compounds of Chemistry – Class 12

Answer 1

Right answer is (c) t2g^3 eg^2

Best explanation: When the field splitting is less than the pairing energy, the energy gap between the two sets of d orbitals is small. This allows the electrons to occupy the higher energy orbitals once the lower orbitals are singly occupied. Thus, the configuration will be t2g^3 eg^2, with one electron in each orbital.